What is cause of rear inside tire wear?
 

2001 Montero XLS (full size, about 165,000 miles). Rear tires wearing faster on inside. About the first 2", and it is very noticeable now. Can this cause be anything other than alignment problems? I heard it could be the "camber" adjustment. I'm not sure how it would be thrown out of wack though. It seems the driverside - rear is a little worse, but I'm not sure..left and right are pretty close. Can this be adjusted at home, like DIY style? I think I see it sagging a little (as if its sagging in middle) when I look at it from behind...